B

second letter in the Irish alphabet, and the first consonant
of the Ogam alphabet. Irish name beithe birch; hence beithe
luis, name of Ogam alphabet, see
IGT Introd. § 4.

O.Ir. b in absolute initial position, after m (imb), and
sometimes after l (Albu) and r (orbae) represents the voiced
labial plosive (Mod. Ir. b), and derives from IE *b, *bh and
*gw
(
GOI § 188
). In other positions it represents
the voiced labial fricative (Mod. Ir. bh), and derives (i) from
the sources already mentioned, together with *p in IE *-pr-,
*-pl- (accabor, díabul), ib.
§ 227
, and (ii) from IE *u in
certain positions (tarb, cubus, etc.). It is possible, however,
that the sound in case (ii) was not phonetically identical
with that in case (i), since they sometimes have different
sandhi treatment; compare dupall (dub-ball) with atrefea
(atreb-fea) and derbráthair, modern dearbhráthair (derbbráthair); compare also ropia (ro-b-bia), and in later
gairpeann (from garbh + peann),
IGT Introd. § 42.
The
-b(-) of the O.Ir. f-future is, according to the latest explanation of this formation (Watkins, Ériu xx), a voicing of
f < *sw.